CNBC – All operations at London’s City Airport were suspended on Tuesday morning after a group of protesters occupied the runway.

The airport tweeted that it was experiencing disruption due to the protest and that it would resume normal service as soon as possible. Police were on the scene, it added.

The airport is situated in the Docklands area, to the east of the capital. After a series of conflicting reports on which campaign group had led the protest, U.K. Black Lives Matter released a statement on its social media accounts.

“London City Airport is shutdown to protest the U.K.’s environmental impact on black people,” it read.

The Evening Standard newspaper earlier reported that protesters had used a boat to reach the runway. London’s Metropolitan Police said that there were nine protesters on the runway and they had erected a tripod and locked themselves together.

“Officers are currently on scene and are negotiating with them. We are awaiting the arrival of specialist resources that are able to ‘unlock’ the protesters. No arrests have been made at this stage,” the police said at 8.30 a.m. London time.

City Airport told CNBC in a statement that: “The runway is currently closed due to protesters on site. Police are present and we will resume normal operations as soon as possible. We apologize to passengers for any inconvenience to their journey.”